Protective clothing of many types is now well known for many and varied uses, such as suits for industrial workers, firemen, forest fire fighters, race car drivers, airplane pilots, and suits for use by military personnel, for protection from fire, vapors and harmful substances. Garments include not only complete, hermetic suits, but also individual garments such as trousers jackets, gloves, boots, hats, head coverings, masks, etc.
Regulations restricting exposure to hazardous environments of various kinds such as the Occupational Safety and Health Act, make it increasingly necessary to have better and more effective kinds of protective garments. In particular, certain requirements by the U.S. Coast Guard and related requirements by other U.S. government or organizations involve a total protective hermetic suit or envelope around the individual person or firemen. These situations involve cleaning up chemical spills or for fighting chemical fires where the chemical materials are unknown and presumed toxic.
The need for such encapsulating suits is for "immediately dangerous to life and health (IDLH)" environments. These suits must be air tight and worn with a self-contained breathing apparatus. The suit must be none absorbent, totally impermeable, and resistant to the widest range of chemicals and reagents. It should also be as fire resistant as possible. Since these suits are being worn by actively working individuals, they should also be flexible, abrasion resistant, lightweight, and should maintain their impermeability while being used.
Such garments presently available are almost invariably of thick construction and heavy in weight, and are often fabricated at least in part from materials impermeable to water or water vapor, such as natural and synthetic rubbers and elastomers, chlorinated rubbers, etc.
Protective clothing comprised of laminates of films have the problem of forming "kinks" when bent so as to restrict movement and become cumbersome.
Protective garments which are also intended to be used in chemical or microbial environments are generally air impervious. The user of the garment because of body heat and from the stress from the work and respiration creates an atmosphere within the protective garment of heat and moisture. The results of the moisture within the headpiece generally causes fogging of the visor which impairs visibility. Even slight fogging of the visor in an external environment containing smoke or clouding can restrict or impair the function of the occupant.
Air into the protective garment is generally provided from a cylinder forming a backpack which supplies the air into the protective garment through the headpiece or through a back portion of the garment. Alternatively, the garment is tethered with a hose from a central supply in which an air hose leads into the headpiece or a back portion. The air supply is intended to provide an internal pressure in the garment to keep it slightly inflated and to cool the occupant. The slight inflation improves the mobility of the occupant as well as permits the air to cool the occupant. The slight inflation is particularly important with garments intended to be used in fire fighting to provide an additional barrier and to prevent adhesion to skin.
Exhaust valves are generally provided to help change the air which is being partially used as well as maintaining a slight pressure within the suit without allowing chemical or smoke seepage through these ports.
For tethered suits, depending on an external air source, it is known to be disadvantageous to be disadvantageous to lead the air into the protective garment through the headpiece. The air hose which is used encumbers movement of the head and any entanglement of the hose can cause removal of the headpiece and subject the occupant to immediate peril. Furthermore, when the air hose is attached to the headpiece the primary area cooled is the head. However, the remainder of the body may not be sufficiently cooled and depending upon the work situation may result in high perspiration which causes discomfort as well as fogging of the visor.
Placement of the air hose on the back portion of the protective garment improves head mobility but reduces the circulation of air across the visor so that visibility can be effected.
Ideally, the air supply into a protective garment should be a able to function to keep the garment slightly inflated to efficiently cool the entire garment and to prevent accumulation of moisture on the inner part of the visor. This should be done with a minimum amount of air flow. Excessive air flow will use up the supply from a portable cylinder too fast, or will require too much flow from an external air pump possibly creating a limited air supply situation.
U.S. Pat. No. 5,082,721 to Smith et al, which is herein incorporated by reference, illustrates a protective garment which can be adapted with the ventilation system of this invention.